Data storage disk clamp apparatus for minimizing disk clamping force and surface area

ABSTRACT

A novel disk clamp apparatus to securely mount one or more data storage disks to the hub of a spindle motor using a minimal amount of clamping force and surface area of the data storage disks is disclosed. A plurality of engagement protrusions disposed on the mating surface of the disk clamp preferably penetrate the mating surface of the data storage disk. Corresponding engagement recesses on the mating surface of the data storage disk are formed from penetration of the engagement protrusions or, alternatively, are preformed on the mating surface of the data storage disk. The engagement protrusions may alternatively be disposed on the data storage disk mating surface, while the corresponding engagement recesses are disposed on the clamp mating surface. In another embodiment, interfacial particles are disposed between the mating surfaces of the disk clamp and the data storage disk which penetrate the respective mating surfaces when pressed together. The interfacial particles may be impregnated into a spacer element which is disposed between the disk clamp and data storage disk mating surfaces, and between the mating surfaces of adjacently stacked data storage disks. Upon application of a clamping force, the sharp prominences of the interfacial particles impregnating the spacer penetrate the mating surfaces of the disk clamp and data storage disk.

FIELD OF THE INVENTION

The present invention relates generally to data storage systems, and,more particularly, to an apparatus for clamping one or more data storagedisks to the hub of a spindle motor using a minimal amount of clampingforce and data storage disk surface area.

BACKGROUND OF THE INVENTION

A typical data storage system includes one or more data storage diskscoaxially mounted on a hub of a spindle motor. The spindle motor rotatesthe disks at speeds typically on the order of several thousandrevolutions-per-minute (RPM). Digital information, representative ofvarious types of data, is typically written to and read from the datastorage disks by one or more transducers, or read/write heads, which aremounted to a rotatably mounted actuator and pass over the surface of therapidly spinning data storage disks.

The actuator typically includes a plurality of outwardly extendingactuator arms, with one or more read/write transducer assemblies beingmounted resiliently or rigidly on the extreme end of the actuator arms.The actuator arms are interleaved into and out of the stack of rotatingdisks, typically by means of a coil assembly mounted to the actuator.The coil assembly generally interacts with a permanent magnet structure,and the application of current to the coil assembly in one polaritycauses the actuator arms and transducers to shift in one direction,while current of the opposite polarity causes the actuator arms andtransducers to shift in an opposite direction.

In a typical digital data storage system, digital data is stored in theform of magnetic transitions on a series of concentric, closely spacedtracks comprising the surface of the magnetizable rigid data storagedisks. The tracks are generally divided into a plurality of sectors,with each sector comprising a number of information fields. One of theinformation fields is typically designated for storing data, while otherfields contain sector identification and synchronization information,for example. Data is transferred to, and retrieved from, specified trackand sector locations by the actuator arms and transducers being shiftedfrom track to track, typically under the control of a controller. Thetransducer assembly typically includes a read element and a writeelement.

Writing data to a data storage disk generally involves passing a currentthrough the write element of the transducer assembly to produce magneticlines of flux which magnetize a specific location of the disk surface.Reading data from a specified disk location is typically accomplished bythe read element of the transducer assembly sensing the magnetic fieldor flux lines emanating from the magnetized locations of the disk. Asthe read element moves over the rotating disk surface, the interactionbetween the read element and the magnetized locations on the disksurface result in electrical pulses being induced in the read element,thereby indicating transitions in the magnetic field.

It is common practice to employ a clamping apparatus to securely clamptogether one or more data storage disks to the hub of a spindle motor.It can be readily appreciated that a data storage disk must be securelymounted to the spindle motor hub to prevent undesirable slippage betweenthe data storage disk and the clamp apparatus which restrains the disksecurely around the hub. Even a minimal amount of slippage between thedisk contact surface and clamp contact surface can, for example, resultin read/write errors, track misregistration errors, and mechanicalfatigue of the spindle motor and data storage disk. A typical clampapparatus, as illustrated in FIG. 3, includes one or more spacers 63disposed between adjacently stacked data storage disks 24, with thedisks 24 and spacers 63 being forced together and secured around thecircular hub 27 of the spindle motor 26 by a disk clamp 61. The disks 24are generally subjected to appreciable levels of axial or radial forces,or a combination of axial and radial forces, resulting from the clampingforce produced by the disk clamp 61. Generally, some degree of bowing,rippling, or other detrimental distortion of the disk 24 surface oftenresults from a non-uniform or non-symmetrical distribution of the forcesimparted to the disks 24 or from subjecting the disks 24 to excessivelyhigh levels of clamping force.

Many disk clamp apparatus have been disclosed, such as those discussedin U.S. Pat. Nos. 5,274,517 and 5,267,106, which purport to provideeffective clamping of a plurality of vertically aligned disks 24 to thehub 27 of a spindle motor 26, while minimizing disk distortion ordetrimental curvature resulting from axial and radial loading forcesimparted on the disks 24 by the disk clamp 61. The disk distortionproduced from excessive loading forces exerted on the disks 24 isparticularly pronounced near the inner diameter of the disk 24, andgradually reduces in magnitude at outer diameter locations on the disk24. If the induced disk distortion is sufficiently pronounced,deleterious contact between the transducer 35 and the distorted disksurface can occur, generally causing damage to both the transducer 35and the affected area of the disk surface. Even in the absence of disk24 and transducer 35 contact, the disk distortion may introduceread/write errors, track misregistration errors, and other performanceerrors of varying severity.

Other disclosed prior art disk clamping schemes employ elastomericmaterial pressed between the disk clamp 61 contact surface 60 and thecontact surface 25 of the data storage disk 24. It is purported thatutilizing elastomeric material in this configuration distributes moreuniformly the loading forces produced by the disk clamp 61 in adirection extending radially outward from the circumference of thecentral aperture of the disk 24. Although it is believed that the use ofelastomeric material in this manner has yet to be incorporated into adata storage system available in the marketplace, use of suchelastomeric materials would likely achieve little success, stemmingprimarily from the mechanical and thermal instability of the relativelylow durometer material, and the perceived necessity to routinely replacethe material during the service life of the data storage system.

In a conventional disk clamping apparatus, the clamping force istypically increased in an attempt to further reduce the possibility ofdisk-to-clamp and disk-to-spacer slippage, thereby increasing the axialloading force on the data storage disk stack. As such, traditionalclamping approaches generally rely primarily on static friction betweenthe disk and clamp mating surfaces in order to reduce the possibility ofdisk-to-clamp and disk-to-spacer slippage. Referring to FIG. 4, there isshown an exaggerated illustration of the contact surfaces 60 and 25 ofthe disk clamp 61 and data storage disk 24, respectively, in accordancewith a prior art clamping apparatus. Although macroscopically thecontact surfaces 60 and 25 may appear substantially smooth, at amicroscopic level, as depicted in FIG. 4, the topographic irregularitiesof the two contact surfaces 60 and 25 provide for some degree of staticfriction between the disk clamp 61 and data storage disk 24 contactsurfaces. In order to enhance the advantages afforded by static frictionbetween the disk and clamp contact surfaces 25 and 60 respectively, thiscontact interface generally comprises a significant percentage of disk24 surface area surrounding the central aperture of the disk 24. Anyincrease in the size of the contact interface between the disk 24 anddisk clamp 61, however, has the adverse effect of reducing the availabledata storing surface area of the disk 24. This concomitant reduction inthe data storage capacity of the disk 24 significantly effects thestorage capacity of a data storage system, and, in particular, small andvery small form factor data storage systems.

In the data storage system manufacturing community, there exists a needto increase the data storing surface area of a data storage disk, and toreduce the amount of disk surface area allocated for mounting the diskto the hub of the spindle motor. There exists a further need tosubstantially reduce or eliminate detrimental disk distortion resultingfrom clamping forces produced by a clamp apparatus when securelymounting the disk to the spindle motor hub. The present inventionfulfills these and other needs.

SUMMARY OF THE INVENTION

The present invention is a novel disk clamp apparatus that providessecure mounting of one or more data storage disks to the hub of aspindle motor using a minimal amount of clamping force and surface areaof the data storage disks. Engagement protrusions disposed on the matingsurface of the disk clamp preferably penetrate the mating surface of thedata storage disk to form a conforming coupling interface. Correspondingengagement recesses on the mating surface of the data storage disk areformed from penetration of the engagement protrusions or, alternatively,are pre-formed on the mating surface of the data storage disk andconfigured to receive corresponding engagement protrusions. Theengagement protrusions may alternatively be disposed on the data storagedisk mating surface, while corresponding engagement recesses aredisposed on the clamp mating surface. In another embodiment, interfacialparticles are disposed between the mating surfaces of the disk clamp andthe data storage disk which penetrate the respective mating surfaceswhen pressed together under forces produced by the disk clamp. Theinterfacial particles may be impregnated into a spacer element which isdisposed between the disk clamp and data storage disk mating surfaces,and between the mating surfaces of adjacently stacked data storagedisks. Upon application of a clamping force, the sharp prominences ofthe interfacial particles impregnating the spacer penetrate the matingsurfaces of the disk clamp and data storage disk.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a data storage system with its upperhousing cover removed;

FIG. 2 is a side plan view of a data storage system comprising aplurality of data storage disks;

FIG. 3 is a generalized illustration of a data storage disk clampingapparatus adapted for securely mounting one or more data storage disksto the hub of a spindle motor;

FIG. 4 is a depiction of the disk-to-clamp contact interface ordisk-to-spacer contact interface of a prior art data storage disk clampapparatus;

FIG. 5 is an exaggerated depiction of a novel coupling interface forpreventing slippage between a data storage disk clamp apparatus and themating surface of a data storage disk;

FIG. 6 is an illustration of a novel coupling interface employing aplurality of engagement protrusions and depressions disposed on themating surfaces of the data storage disk and clamp apparatus;

FIG. 7 is an illustration of a novel coupling interface employing aplurality of radial ridges disposed on the surface of a data storagedisk for enhancing coupling between the mating surfaces of the datastorage disk and clamp apparatus;

FIG. 8 is an exaggerated illustration of a novel coupling interfaceemploying a plurality of interfacial particles disposed between andpenetrating into the mating surfaces of a data storage disk and a clampapparatus;

FIG. 9 is an illustration of a novel compliant spacer impregnated with aplurality of interfacial particles and disposed between adjacent diskmating surfaces and the mating surface of a clamp apparatus; and

FIG. 10 is an exaggerated side plan view of a novel compliant spacerimpregnated with a plurality of interfacial particles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and more particularly to FIGS. 1 and 2,there is shown a data storage system 20 having one or more rigid datastorage disks 24 stacked coaxially in a tandem spaced relationship whichrotate about a common spindle motor 26 at a relatively high rate ofrotation. Each disk 24 is typically formatted to include a plurality ofspaced concentric tracks 50, with each track being partitioned into aseries of sectors 52. The disks 24 may alternatively be formatted toinclude one or more spiraled tracks.

An actuator 30 typically includes a plurality of interleaved actuatorarms 28, with each arm having at least one transducer 35 mounted thereonfor reading and writing information onto the data storage disks 24. Theactuator 30 is usually mounted to a stationary actuator shaft 32, androtates thereon to move the actuator arms 28 and transducers 35 into andout of the stack of data storage disks 24. A coil assembly 36, mountedto a coil frame 34 of the actuator 30, generally rotates within a gap 44defined between the upper and lower magnet assemblies 40 and 42 of apermanent magnet structure 38, causing the actuator arms 28 andtransducers 35 to sweep over the surfaces of the data storage disks 24.The spindle motor 26 typically comprises a poly-phase a.c. motor or,alternatively, a d.c. motor energized by a power supply 46 for rotatingthe data storage disks 24.

The coil assembly 36 and the upper and lower magnet assemblies 40 and 42of the permanent magnet structure 38 operate in cooperation as anactuator voice coil motor (VCM) 82 responsive to control signalsproduced by a controller 58. The actuator VCM 82 produces a torquingforce on the actuator coil frame 34 when control currents of varyingdirection and magnitude flow in the coil assembly 36 in the presence ofa magnetic field produced by the permanent magnet structure 38. Thetorquing forces imparted on the actuator coil frame 34, in turn, causecorresponding rotational movement of the actuator arms 28 andtransducers 35 in directions dependent on the polarity of the controlcurrents flowing in the coil assembly 36. A controller 58 preferablyincludes control circuitry that coordinates the transfer of data to andfrom the data storage disks 24, and cooperates with the actuator VCM 82to move the actuator arms 28 and transducers 35 to prescribed track 50and sector 52 locations when reading and writing data to the disks 24.

Turning now to FIG. 5, there is shown a depiction of the surfacetopography of a coupling interface 66 illustrating a novel engagementconfiguration between a data storage disk 24 and a clamp apparatus 61for securely mounting the data storage disk 24 to a circular hub 27 of aspindle motor 26. In one preferred embodiment, a first mating surface 68preferably includes a plurality of asperities or engagement protrusions72 having relatively small radii of curvature. In the embodimentillustrated in FIG. 5, the engagement protrusions 72 penetrate into asecond mating surface 70 when the first mating surface 68 and secondmating surface 70 are brought into contact under a clamping forceproduced by the disk clamp apparatus 61. The penetration of theengagement protrusions 72 into the second mating surface 70 results inthe production of corresponding engagement recesses 74 on the secondmating surface 70. It should be understood that the first mating surface68 and the second mating surface 70 are respectively representative ofthe mating surfaces of a disk clamp 61 and a data storage disk 24.Alternatively, the first mating surface 68 is representative of themating surface of the data storage disk 24, while the second matingsurface 70 is representative of the mating surface of the disk clamp 61.Further, the first and second mating surfaces 68 and 70 may instead berespectively representative of the mating surfaces of a spacer elementand a data storage disk, with the spacer element being disposed betweentwo adjacently stacked disks 24.

It is well understood that penetration of one material into anothermaterial results in a coupling interface that is substantially moreresistant to torque loading forces than a contact interface relyingmerely on the static friction between the two materials to resist suchforces. The unique disk-to-clamp coupling interface 66, in contrast to aprior art disk-to-clamp contact interface 65 which relies solely uponfrictional resistance between the contact surfaces 62 and 64, restrictsor virtually precludes radial movement or other positional shiftingbetween the clamp and disk mating surfaces 68 and 70 during rotation ofthe data storage disk 24. Penetration of the engagement protrusions 72into corresponding engagement recesses 74 provides significantlyenhanced slip resistance to torque loading forces which must overcomethe shear stress of the engagement protrusion 72 material in addition tothe static friction associated with the substantially roughenedtopography of the first and second mating surfaces 68 and 70. The torqueloading required to overcome the shear stress of the engagementprotrusion 72 material is typically orders of magnitude higher than thetorque loading that can be sustained without slippage between the matingsurfaces 68 and 70 when relying solely on static friction between thetwo surfaces 68 and 70.

The second mating surface 70, illustrated in FIG. 5, preferablyrepresents the mating surface of the data storage disk 24 and comprisesonly a small percentage of the total disk 24 surface area extendingradially outward from the central aperture 92 of the disk 24. It isgenerally recognized that a conventional disk clamping apparatus impartssignificant axial and radial forces to the sensitive surface of the datastorage disk 24, with maximum stress being localized along the innerdiameter of the central disk aperture 92. Varying degrees of undesirabledisk 24 surface curvature or distortion, which is particularlypronounced near the inner diameter of the disk 24 proximate the centraldisk aperture 92, typically results from a nonuniform distribution ofaxial and radial forces produced by the clamp apparatus 61. The novelcoupling interface 66, as illustrated in FIG. 5, provides matingengagement between the mating surfaces 68 and 70 of the disk clamp 61and data storage disk 24 by the application of clamping forcessignificantly lower that those that would otherwise be required tomaintain secured engagement between the contact surfaces 25 and 60 of aconventional data storage disk 24 and clamp apparatus 61.

More specifically, the penetration of the first mating surface 68 intothe second mating surface 70 greatly enhances the slip resistancebetween the two surfaces 68 and 70 when under the influence of torqueloading forces and other forces associated with relatively high rates ofspindle motor 26 and data storage disk 24 rotation. When assembling thedata storage disk 24 and hub 27/spindle motor 26 structure, the matingsurfaces 68 and 70 of the disk clamp 61 and data storage disk 24 arerespectively brought into close proximity under the application of anaxial force produced by the clamp apparatus 61 sufficient to causepenetration of the engagement protrusions 72 into the relatively softersecond mating surface 70, thereby producing corresponding engagementrecesses 74. It is noted that the second mating surface 70 of the datastorage disk 24 may have hardness characteristics substantiallyequivalent to those of the first mating surface 68 of the clamp 61. Oncepenetration has occurred, the axial loading force imparted to the datastorage disk 24 by the disk clamp apparatus 61 can typically be reduced.

The reduced level of clamping force required to prevent slippage orshifting respectively between the disk clamp 61 and disk 24 matingsurfaces 68 and 70 directly results from the novel coupling interface 66which exploits the sheer strength of the engagement protrusion 72material. It has been determined that only a fraction of the totalasperities or engagement protrusions 72 disposed on the first matingsurface 68 need penetrate the second mating surface 70 to ensure securedcoupling between the data storage disk 24 and disk clamp 61.Accordingly, the occurrence and magnitude of undesirable disk 24curvature typically resulting from appreciable levels of axial andradial loading forces imparted by the clamping apparatus 61 issubstantially reduced or eliminated.

Another important advantage of the novel coupling interface between thedata storage disk 24 and disk clamp apparatus 61 concerns the minimizingof disk 24 surface area required to securely clamp the disk 24 to thehub 27 of the spindle motor 26. The substantially strengthened contactinterface 66 between the mating surfaces 68 and 70 of the disk clamp 61and data storage disk 24 provides for a substantial reduction in theamount of disk 24 surface area required to contact and engage the diskclamp apparatus 61. The disk 24 contact surface area that wouldotherwise be designated for use when mounting the disk 24 to the hub 27can instead be allocated for the storage of data, thereby increasing thestorage capacity of the data storage disk 24.

As the demand for high capacity data storage disks increases, minimizingof the disk 24 surface area required for clamping the disk 24 to themotor spindle hub 27 becomes of significant importance. A moderateincrease in the disk surface area dedicated for non-data storage usesfor disks employed in small and very small form factor data storagesystems, for example, can result in a dramatic reduction in the overalldata storage capacity of the disk. It is noted that such small formfactor data storage disks typically have diameters on the order of 4.6centimeters. The novel disk-to-clamp coupling scheme illustrated in FIG.5 minimizes the disk surface area required to effectively mount andsecure the data storage disk 24 to the spindle motor hub 27.

Referencing now FIG. 6, there is shown an alternative preferredembodiment of the novel disk-to-clamp coupling interface 80. The firstand second mating surfaces 82 and 84 of the disk clamp 61 and datastorage disk 24, respectively, are shown as having a relatively smoothtopography. In the embodiment illustrated in FIG. 6, the second matingsurface 84 is preferably representative of the substantially smoothmating surface of a glass or ceramic data storage disk 24, and the firstmating surface 82 is preferably representative of the mating surface ofthe clamp apparatus 61. In one embodiment, the mating surface 82 of thedisk clamp 61 is preferably constructed from a material that is softerthan the glass or ceramic mating surface 84 of the disk 24, such asaluminum, for example. In another embodiment, the materials forming themating surfaces of the disk clamp 61 and disk 24 have substantially thesame hardness. It is noted that ceramic material suitable for use in thefabrication of a data storage disk 24 typically exhibits a surfacehardness of approximately 10 to 100 times that of aluminum.

In one embodiment, the second mating surface 84 of a glass or ceramicdata storage disk 24 is preferably etched or otherwise fabricated toinclude a plurality of engagement protrusions 86 for penetrating into,and engaging with, corresponding engagement depressions 88 provided onthe first mating surface 82 of the disk clamp 61. Alternatively, thesecond mating surface 84 of the data storage disk 24 may be roughened bymechanical or chemical means to provide a high-friction contact surface,with engagement protrusions 86 of varying configuration being receivedby corresponding engagement depressions 88 disposed on the disk clamp 61mating surface 82. It is to be understood that the engagementprotrusions and depressions 86 and 88 shown as having substantiallytriangular cross-sectional configurations may instead be fabricated toexhibit substantially rectangular cross sections. Further, othercross-sectional configurations and geometries may be appropriate fordata storage disks 24 and disk clamp 61 apparatus having varyingconfigurations and differing construction materials. It is to be furtherunderstood that a plurality of engagement protrusions 86 may be disposedon the mating surface of the disk clamp 61 rather than the data storagedisk 24 mating surface 84 as illustrated in FIG. 6. A plurality ofengagement depressions 88 may, for example, be mechanically orchemically developed on the mating surface 84 of the data storage disk24.

One advantage of employing a chemical etching process in the fabricationof the engagement protrusions 86 on the surface of a glass or ceramicdata storage disk 24 concerns the ability to optimally design andcontrol the configuration and topography of the mating surface 84 of thedisk 24. For example, as illustrated in FIG. 7, a series of radialengagement ridges 94 or spokes may be developed on the mating surface 84of a glass or ceramic disk 24. The radial engagement ridges 94preferably engage corresponding radial engagement depressions disposedon the mating surface of the disk clamp 61. The conforming engagementbetween the engagement ridges 94 of the disk 24 and correspondingengagement depressions disposed on the disk clamp 61 mating surface 82substantially increases the resistance to radial slippage or otherpositional shifting that might otherwise occur as the disk 24 and clampapparatus 61 rotate at relatively high rates of rotation during normaloperation of the data storage system 20. A chemical etching process ispreferably employed to produce the engagement ridges 94 on the disk 24mating surface 84, and can be advantageously controlled to maintaincoplanarity between the summits of the ridges 94 and the mating surfacearea 95 of the disk 24 between the engagement ridges 94.

Another embodiment of the novel disk-to-clamp coupling interface 100 isillustrated in FIG. 8. In this embodiment, the first and second matingsurfaces 102 and 104 are illustrated as having a relatively smoothsurface topography, and preferably exhibit substantially similar surfacehardness characteristics. It is generally advantageous to employmaterials having similar thermal expansion coefficients andcharacteristics in order to maintain a predictable and stable operatingenvironment which is typically subject to moderate fluctuations inoperating temperature. In accordance with this embodiment, a pluralityof interfacial particles 106 are disposed between the mating surfaces102 and 104 of the disk clamp 61 and data storage disk 24, respectively.The interfacial particles 106 are preferably fabricated from materialharder than the material of the mating surfaces 102 and 104. Theinterfacial particles 106 preferably include at least two sharpprominences 108 and 110 having relatively small radii of curvature.

With the interfacial particles distributed approximately uniformly overthe mating surface 104 of the data storage disk 24, the disk clamp 61and disk 24 mating surfaces 102 and 104 are brought into close proximityunder the application of a clamping force produced by the disk clamp 61.The applied clamping force causes the sharp prominences 108 and 110 topenetrate respectively into the disk clamp 61 and disk 24 matingsurfaces 102 and 104. The shear stress of the interfacial particles 106in combination with static friction between the disk clamp 61 and disk24 mating surfaces 102 and 104, respectively, virtually eliminates diskslippage even at relatively low axial loading force levels.

It is generally desirable to maintain the disk clamp 61 and data storagedisk 24 mating surfaces 102 and 104 in a substantially parallelrelationship. As such, the addition of the interfacial particles 106interposing the mating surfaces 102 and 104 should be of an appropriatesize and shape to prevent disturbance of the coplanarity of the matingsurfaces 102 and 104. Ceramic materials, such as silicon dioxide,aluminum oxide, and titanium carbide, are suitable materials forfabricating the interfacial particles 106. These and other similarceramic materials typically have crystalline structures that promotecleaving along grain boundaries. This results in the production ofparticles having relatively sharp edges or prominences. The sharp edgespermit easy penetration of the interfacial particles 106 into therelatively softer material comprising the disk clamp 61 and data storagedisk 24 mating surfaces 102 and 104, respectively.

The relatively inert and stable nature of the ceramic interfacialparticles 106 represents another significant advantage of the embodimentillustrated in FIG. 8. The ceramic material from which the interfacialparticles 106 are fabricated generally does not react with the chemistryof the disk 24 mating surface 104 or with other materials used in theconstruction of the data storage system 20. Such ceramic materials, forexample, are associated with extremely low levels of undesirableoutgassing. Another significant advantage of employing ceramic materialconcerns the ability to control the size and configuration of theinterfacial particles 106. For example, a standard deviation of 0.1microns for a 2 micron silicon oxide interfacial particle 106 isroutinely obtainable by conventional fabrication methods.

Turning now to FIGS. 9 and 10, there is shown an alternative embodimentin which a compliant spacer 120, impregnated with a plurality ofinterfacial particles 106, is disposed respectively between the diskclamp 61 and data storage disk 24 mating surfaces 122 and 124. It may bedesirable to contain the interfacial particles 106 between the matingsurfaces 122 and 124 of the disk clamp 61 and data storage disk 24 toprevent accidental dislodging of the interfacial particles 106 into theinterior of the data storage system housing 21. To preclude any suchdeleterious escape of the interfacial particles 106 into the relativelycontaminant-free environment surrounding the data storage disks 24 andspindle motor assembly 26, a spacer element 120 may be employed as acarrier for the interfacial particle matrix 106.

The spacer 120, for example, may be fabricated in the following manner.The spacer 120 is preferably formed from a polymeric or other compliantmaterial capable of incorporating various fillers to obtain sufficientrigidity. Glass fibers, carbon fillers, and other similar fillermaterial may be introduced into the polymeric matrix to achieve thedesired structural rigidity of the spacer 120. The spacer 120 is groundflat so that its contact surfaces are substantially coplanar. The spacer120, preferably circular in configuration and having an inner apertureadapted for installation around the circular hub 27 of the spindle motor26, is then placed between two plates that have a hardness substantiallyequivalent to or harder than the interfacial particles 106. Theinterfacial particles 106 are then distributed approximately uniformlyon the coplanar contact surfaces of the spacer 120, and then pressedinto the contact surfaces of the spacer 120 by application of force tothe two plates. Following the impregnation of the interfacial particles106 into the spacer 120, the spacer 120 is then removed and cleaned by apressurized water rinse or ultrasonic cleaning process. The spacer maythen be installed into the data storage system 20.

As shown in FIG. 9, a plurality of data storage disks 24 are preferablymounted in a tandem, spaced relationship around the circular hub 27 of aspindle motor 26. The compliant spacer 120, impregnated with interfacialparticles 106, is preferably installed between the mating surfaces 124of each of the adjacently stacked data storage disks 24. A compliantspacer 120 is also installed between the mating surface 122 of the diskclamp 61 and the mating surface 124 of an adjacent data storage disk 24.In this configuration, the sharp prominences 108 and 110 of theinterfacial particles 106 impregnating the compliant space 120penetrates the adjacent mating surfaces 124 of the data storage disks 24and the mating surfaces 122 of the disk clamp 61. By virtue of theinterfacial particles 106 disposed between adjacent disk 24 and diskclamp 61 mating surfaces, only a minimal amount of axial loading forceproduced by the disk clamp 61 need be applied to securely clamp one ormore data storage disks 24 to the hub 27 of the spindle motor 26.Further, only a minimal amount of disk 24 surface area must be allocatedfor clamping purposes, thereby maximizing the data storage capacity ofthe data storage disk.

It will, of course, be understood that various modifications andadditions can be made to the embodiments discussed hereinabove withoutdeparting from the scope or spirit of the present invention.Accordingly, the scope of the present invention should not be limited bythe particular embodiments discussed above, but should be defined onlyby the claims set forth below and equivalents of the disclosedembodiments.

What is claimed is:
 1. A clamp apparatus for clamping a data storagedisk around a circular hub, comprising:a data storage disk disposed onthe circular hub and having a substantially rigid mating surface; aclamp disposed on the circular hub and having a substantially rigidmating surface the data storage disk being disposed between the clampand the circular hub, and engagement protrusions integrally formed onone of the disk and clamp mating surfaces, the engagement protrusionspenetrating the other one of the disk and clamp mating surfaces to formcorresponding engagement recesses; wherein engagement of the engagementprotrusions and the corresponding engagement recesses under a clampingforce provided by the clamp prevents movement between the clamp and diskmating surfaces during rotation of the data storage disk and circularhub.
 2. A clamp apparatus for clamping a data storage disk around acircular hub, comprising:a data storage disk disposed on the circularhub and having a substantially rigid mating surface; a clamp disposed onthe circular hub and having a substantially rigid mating surface, thedata storage disk being disposed between the clamp and the circular hub;a plurality of engagement protrusions having substantially triangularcross sections and being integrally formed on one of the disk and clampmating surfaces; and a plurality of engagement depressions havingsubstantially triangular cross sections and being formed on the otherone of the disk and clamp mating surfaces and adapted for receiving theengagement protrusions; wherein engagement of the engagement protrusionsand the engagement depressions under a clamping force provided by theclamp prevents movement between the clamp and disk mating surfacesduring rotation of the data storage disk and circular hub.
 3. A clampapparatus for clamping a data storage disk around a circular hub,comprising:a data storage disk disposed on the circular hub and having asubstantially rigid mating surface; a clamp disposed on the circular huband having a substantially rigid mating surface, the data storage diskbeing disposed between the clamp and the circular hub and; a pluralityof interfacial particles having sharp prominences integrally formed onone of the disk and clamp mating surfaces and protruding into the otherone of the disk and clamp mating surfaces; wherein protrusion of theplurality of interfacial particles into the other one of the disk andclamp mating surfaces under a clamping force provided by the clampprevents movement between the clamp and disk mating surfaces duringrotation of the data storage disk and circular hub.
 4. An apparatus asclaimed in claim 3, wherein the interfacial particles comprise ceramicmaterial, and the disk and clamp mating surfaces comprise materialsofter than the ceramic material of the interfacial particles.
 5. Aclamp apparatus for clamping a data storage disk around a circular hub,comprising:a data storage disk disposed on the circular hub and having asubstantially rigid mating surface; a clamp disposed on the circular huband having a substantially rigid mating surface, the data storage diskbeing disposed between the clamp and the circular hub and; a pluralityof engagement protrusions integrally formed on one of the disk and clampmating surfaces and having a hardness greater than a hardness of theother one of the disk and clamp mating surfaces so as to penetrate theother one of the disk and clamp mating surfaces to form a plurality ofengagement recesses thereon; wherein clamped engagement between theengagement protrusions and the engagement recesses restricts movementbetween the clamp and disk mating surfaces during rotation of the datastorage disk and circular hub.
 6. A clamp apparatus for clamping a datastorage disk around a circular hub, comprising:a data storage diskdisposed on the circular hub and having a substantially rigid matingsurface; a clamp disposed on the circular hub and having a substantiallyrigid mating surface, the data storage disk being disposed between theclamp and the circular hub; a plurality of engagement protrusionsintegrally formed on one of the disk and clamp mating surfaces; and aplurality of engagement recesses formed on the other one of the disk andclamp mating surfaces; wherein the plurality of engagement protrusionsdisposed on one of the disk and clamp mating surfaces comprises a sharpprominence that penetrates the other one of the disk and clamp matingsurfaces to form at least one of the plurality of engagement recesses,and clamped engagement between the engagement protrusions and engagementrecesses restricts movement between the clamp and disk mating surfacesduring rotation of the data storage disk and circular hub.
 7. A clampapparatus for clamping a data storage disk around a circular hub,comprising:a data storage disk disposed on the circular hub and having asubstantially rigid mating surface; a clamp disposed on the circular huband having a substantially rigid mating surface, the data storage diskbeing disposed between the clamp and the circular hub; a plurality ofengagement protrusions integrally formed on one of the disk and clampmating surfaces and having substantially triangular cross sections; anda plurality of engagement recesses formed on the other one of the diskand clamp mating surfaces and having substantially triangular crosssections adapted for receiving corresponding engagement protrusions;wherein clamped engagement between the engagement protrusions andengagement recesses restricts movement between the clamp and disk matingsurfaces during rotation of the data storage disk and circular hub.
 8. Aclamp apparatus for clamping a data storage disk around a circular hub,comprising:a data storage disk, comprising ceramic material, disposed onthe circular hub and having a substantially rigid mating surface; aclamp disposed on the circular hub and having a substantially rigidmating surface, the data storage disk being disposed between the clampand the circular hub; a plurality of engagement protrusions integrallyformed on the mating surface of the disk; and a plurality of engagementrecesses formed on the mating surface of the clamp; wherein clampedengagement between the engagement protrusions on the disk mating surfaceand corresponding engagement depressions disposed on the clamp matingsurface restricts movement between the clamp and disk mating surfacesduring rotation of the data storage disk and circular hub.
 9. Anapparatus as claimed in claim 8, wherein the engagement protrusionscomprise a plurality of elongated ridges disposed on the mating surfaceof the disk extending radially outward from the center of the disk, theelongated ridges on the disk engaging corresponding elongateddepressions disposed in the mating surface of the clamp.
 10. A clampapparatus for clamping a data storage disk around a circular hub,comprising:a data storage disk disposed on the circular hub and having asubstantially rigid mating surface; a clamp disposed on the circular huband having a substantially rigid mating surface, the data storage diskbeing disposed between the clamp and the circular hub; a plurality ofengagement protrusions integrally formed on one of the disk and clampmating surfaces; and a plurality of engagement recesses formed on theother one of the disk and clamp mating surfaces; wherein a plurality ofinterfacial particles having sharp prominences is disposed on one of themating surfaces of the disk and clamp to form the engagement protrusionsthat penetrate the other one of the disk and clamp mating surfaces toform the engagement recesses, and clamped engagement between theengagement protrusions and engagement recesses restricts movementbetween the clamp and disk mating surfaces during rotation of the datastorage disk and circular hub.
 11. A clamp apparatus for clamping a datastorage disk around a circular hub, comprising:a data storage diskdisposed on the circular hub and having a substantially rigid matingsurface; a clamp disposed on the circular hub and having a substantiallyrigid mating surface, the data storage disk being disposed between theclamp and the circular hub; a plurality of engagement protrusionsintegrally formed on one of the disk and clamp mating surfaces; and aplurality of engagement recesses formed on the other one of the disk andclamp mating surfaces; wherein a plurality of interfacial particles areimpregnated into compliant material forming a spacer, the spacer beingdisposed between the disk and clamp mating surfaces and the interfacialparticles respectively protruding into the disk and clamp matingsurfaces, and clamped engagement between the engagement protrusions andengagement recesses restricts movement between the clamp and disk matingsurfaces during rotation of the data storage disk and circular hub. 12.A system for storing data, comprising:a housing; a data storage diskhaving a substantially rigid mating surface; a spindle motor mounted tothe housing and adapted for rotating the data storage disk; an actuatormovably mounted to the housing; a transducer mounted to the actuator;and a clamp apparatus for clamping a data storage disk around a circularhub, comprising:a clamp disposed on the circular hub and having asubstantially rigid mating surface, the data storage disk being disposedbetween the clamp and the circular hub; engagement protrusionsintegrally formed on one of the disk and clamp mating surfaces andpenetrating at a plurality of penetration locations the other one of thedisk and clamp mating surfaces to form corresponding engagementrecesses; wherein penetration of the engagement protrusions at theplurality of penetration locations to form the corresponding engagementrecesses under a clamping force provided by the clamp prevents movementbetween the clamp and disk mating surfaces during rotation of the datastorage disk and circular hub.
 13. A system for storing data,comprising:a housing; a data storage disk having a substantially rigidmating surface; a spindle motor mounted to the housing and adapted forrotating the data storage disk; an actuator movably mounted to thehousing; a transducer mounted to the actuator; and a clamp apparatus forclamping a data storage disk around a circular hub, comprising:a clampdisposed on the circular hub and having a substantially rigid matingsurface, the data storage disk being disposed between the clamp and thecircular hub; a plurality of engagement prominences having substantiallytriangular cross sections and integrally formed on one of the disk andclamp mating surfaces; and a plurality of engagement depressions havingsubstantially triangular cross sections and formed on the other one ofthe disk and clamp mating surfaces and adapted for receivingcorresponding engagement prominences, wherein engagement of theengagement depressions and the corresponding engagement prominencesunder a clamping force provided by the clamp prevents movement betweenthe clamp and disk mating surfaces during rotation of the data storagedisk and circular hub.
 14. A system for storing data, comprising:ahousing; a data storage disk having a substantially rigid matingsurface; a spindle motor mounted to the housing and adapted for rotatingthe data storage disk; an actuator movably mounted to the housing; atransducer mounted to the actuator; and a clamp apparatus for clamping adata storage disk around a circular hub, comprising:a clamp disposed onthe circular hub and having a substantially rigid mating surface, thedata storage disk being disposed between the clamp and the circular hub;and a plurality of interfacial particles having sharp prominencesdisposed on one of the disk and clamp mating surfaces and protrudinginto the other one of the disk and clamp mating surfaces; whereinprotrusion of the interfacial particles into the other one of the diskand clamp mating surfaces under a clamping force provided by the clampprevents movement between the clamp and disk mating surfaces duringrotation of the data storage disk and circular hub.
 15. A system forstoring data, comprising:a housing; a data storage disk having asubstantially rigid mating surface; a spindle motor mounted to thehousing and adapted for rotating the data storage disk; an actuatormovably mounted to the housing; a transducer mounted to the actuator;and a clamp apparatus for clamping a data storage disk around a circularhub, comprising:a clamp disposed on the circular hub and having asubstantially rigid mating surface, the data storage disk being disposedbetween the clamp and the circular hub; coupling means, integrallyformed on one of the disk and clamp mating surfaces, for penetrating ata plurality of penetration locations the other one of the disk and clampmating surfaces; and a compliant spacer having first and second surfacesrespectively impregnated with interfacial particles, the spacer beingdisposed between the disk and clamp mating surfaces such that theinterfacial particles impregnating the first and second spacer surfacesrespectively protrude into the disk and clamp mating surfaces; whereinthe coupling means, under a clamping force provided by the clamp,prevents movement between the clamp and disk mating surfaces duringrotation of the data storage disk and circular hub.
 16. An apparatus asclaimed in claim 15, wherein a plurality of data storage disks isdisposed on the circular hub, and a compliant spacer having first andsecond surfaces respectively impregnated with interfacial particles isdisposed between mating surfaces of adjacently mounted disks.